A Study of Low Global Warming Potential Refrigerants to Replace R123 for Chiller Application

Abstract

The raising concern about climate change and global warming provides the searching for more environmental friendly refrigerants for chiller applications. In this study, an investigation for low GWP refrigerants to replace R123 has been conducted for evaluation for chiller systems. R1233zd(E), R1234ze(E), R1234yf, R290, and R600 have been compared with R123 under different effecting factors. R1233zd(E) and R600 display a close COP performance when compared with the baseline R123, while other R123 alternatives present a low COP level (more than 5% COP decrease from baseline R123). R290 displays the highest value of the compressor impeller speed while R123 the lowest. In general, R1233zd(E) is preferred for drop-in option to replace R123 due to close COP and unit capacity by volume. R1234ze(E), R1234yf, and R290 are preferred for chiller down-size options. Increasing evaporating temperature from 1°C to 5°C can display more than 15% COP enhancement and it does not have the significant change for the mass flow rate and the compressor impeller speed. The condensing temperature increase from 30°C to 40°C has significant influence on the system COP drop, with \(\sim30\)% COP decrease there. Increasing the compressor isentropic efficiency from 0.6 to 0.8 can make the COP increased by more than 30%, and make the compressor power consumption to be reduced by more than 24%. From the single-stage cycle chiller system to the two-stage cycle chiller system, the COP can be improved by 3.0% for R123, 3.1% for R1233zd(E), 4.4% for R1234ze(E), 5.1% for R1234yf, 4.0% for R290, and 3.5% for R600, respectively. In general, R1234yf is more sensitive for the cycle improvement.